GATE XE Chemistry of high polymers PYQs & Answers — Page 2

Questions 11–20 of 66. Imported answers require independent review unless marked reviewed.

The crystallization of a polymer can only proceed in a temperature range limited to glass transition temperature (T_g) on the lower side, the equilibrium melting point (T_m^o) on the higher side. Around T_g, the mobility of the polymer chains is lower, while in the proximity of T_m^o, crystallization is inhibited.

In a miscible polymer blend with only one component being crystalline, which option(s) correctly match(es) the Temperature conditions with Events?

Temperature conditions: P — The T_g of the amorphous component is lower than the crystallizable one; Q — The T_g of the amorphous component is higher than the crystallizable one; R — The blend T_g is higher than the T_m^o of the crystallizable one.

Events: 1 — The temperature range over which crystallization can occur becomes smaller; 2 — Crystallization is inhibited; 3 — The crystallization envelope (T_m^o − T_g) is widened; 4 — Crystallization is favored.

Your answerSelect all correct options. You can choose more than one.

P-3; Q-2; R-4

P-3; Q-1; R-2

P-4; Q-1; R-3

P-4; Q-1; R-2

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The heat of polymerization of ethylene is 25 Kcal/mol. The amount of heat generated during the polymerization of 5.6 Kg polyethylene is ______ Kcal. (Round off to the nearest integer)

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The density of an amorphous polymer is 0.77 g cm⁻³ and that of its crystalline counterpart is 0.9 g cm⁻³. The density of a semi-crystalline sample of this polymer is found to be 0.88 g cm⁻³.

The degree of crystallinity (on weight basis) of this semi-crystalline sample is ________. (Round off to two decimal places)

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Phenol-formaldehyde resin is prepared by

Your answerChoose one option.

condensation polymerization

cation polymerization

anionic polymerization

ring opening polymerization

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Melting phenomenon in a semi-crystalline polymer is a ________ order phase transition.

Your answerChoose one option.

zeroth

first

second

third

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Which of the following polymers is/are synthesized by ring opening polymerization?

Your answerSelect all correct options. You can choose more than one.

Poly(lactic acid)

Poly(ε-caprolactone)

Poly(styrene)

Poly(aniline)

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The propagation step of a free radical copolymerization is represented by the following possible reaction steps:

P1:

, rate constant =

P2:

, rate constant =

P3:

, rate constant =

P4:

, rate constant =

where,

and

are two monomers and

and

are the active radicals of

and

, respectively.

(

) represents the rate constant of each step as shown above.

If the reactivity ratios of

and

are expressed as:

and

, respectively, and feed mole ratio,

is expressed as

(where,

and

are the concentrations of

and

, respectively), the probability of the reaction P2 is ______.

Your answerChoose one option.

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Polyamide 66 is prepared by the condensation polymerization of 0.08 mol of hexamethylene diamine with 0.08 mol of adipic acid. At the end of the polymerization reaction, the reaction product contained 0.002 mol of unreacted carboxylic acid groups. The molecular weight of the repeat unit of polyamide 66 is 226 g mol

. The number-average molecular weight (

) of the polyamide 66 in the reaction product is ______ g mol

(rounded off to the nearest integer).

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Which one of the monomers given is used in the synthesis of cellulose?

Your answerChoose one option.

Fructose

Lactic acid

Galactose

Glucose

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A high molecular weight polymer passes through different zones from the hopper to the die in an extruder. Among the options given, identify the correct match between the zones and their key functions.

Zones: P — Metering zone; Q — Compression zone; R — Feed zone; S — Working zone.

Key functions: 1 — High shear forces for effective mixing; 2 — Receives the charge or feed; 3 — Melts the charge or feed through heat conducted by the heating element; 4 — The charge or feed acquires a constant flow rate imparted by the helical flight of the screw.

Your answerChoose one option.

P-4; Q-3; R-2; S-1

P-3; Q-4; R-1; S-2

P-4; Q-1; R-2; S-3

P-3; Q-1; R-2; S-4

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GATE XE Chemistry of high polymers PYQs

Question 126

Question 127

Question 128

Question 110

Question 111

Question 118

Question 119

Question 127

Question 110

Question 114